ISLAMABAD (Reuters) - Up to 600 militants from Afghanistan attacked two Pakistani villages Wednesday, Pakistani officials said, the latest in a campaign of large-scale raids on civilians and security forces.
Militants stormed the border villages of Nusrat Dra and Kharo in the Upper Dir region, fighting soldiers and pro-government tribal militia.
"According to reports from the two villages, between 550-600 militants launched the attack at around 5 in the morning and the fighting continued for several hours," police official Abdul Sattar told Reuters.
Another official said four pro-government tribesmen who fought along with troops were wounded in the attack.
Pakistan says more than 55 soldiers have been killed in several attacks from across the border over the past month. The raids have raised tension between the neighbours as they battle protracted insurgencies by Taliban and al Qaeda-linked militants.
Pakistani Taliban fighters who fled to Afghanistan in the face of army offensives have joined allies in Afghanistan to regroup and threaten Pakistan's border regions again, analysts say.
Pakistan blames Afghanistan for giving refuge to militants on its side of the border, leaving its troops vulnerable to counter-attack when it chases them out of the tribal areas and into Afghanistan.
Kabul in turn has blamed Pakistan for killing dozens of civilians in weeks of cross-border shelling that has angered Afghans at street level and senior officials alike.
The lawless frontier is home to some of the world's most dangerous militant groups, who are intricately linked and cross back and forth to carry out operations.
Separately, Pakistan-based militants attacked troops in another tribal region of North Waziristan Wednesday. Intelligence officials said troops backed by helicopter gunships killed three militants and wounded five in the firefight. Five soldiers were also wounded.
The Pakistani Taliban have been stepping up attacks against the state after warning they would avenge the killing of Osama bin Laden by U.S. special forces on May 2.
After bin Laden's death, the United States reiterated calls for Pakistan to crack down harder on militants, especially those who cross over to Afghanistan to attack Western forces.
The Pakistan army said Monday it had launched an air and ground offensive against militants in the tribal region of Kurram which also borders Afghanistan.